To confirm: (9.6 onwards)
1) Just create a LUN without using prefix/suffix-size
2) To confirm prefix/suffix-size value, run this command:
::> set diag
Warning: These diagnostic commands are for use by NetApp personnel only.
Do you want to continue? {y|n}: y
::*> lun show -ostype solaris -fields prefix-size,suffix-size
It should return zero.